Nirjala : Without even waterVrat : FastingRatri Jagran :
Keeping awake during nightBhajan : Singing religious songsKirtan :
Chanting names of gods.Grihasta : Men having FamilySanyasi : Those
who have renounced the family life

Birthday of Bhagwan Krishna. In Mithilanchal,
the day is celebrated by installing the idol of Krishna and Radha. At
places idols of Nand and Yashoda as well as Rukmini, Satyabhama are also
installed. Even without idols, Shri Krishna, Balbhadra (brother), Vasudeva
(father), Nand (foster father), Yashoda (foster mother), Deoki (mother),
Rohini (wife of Vasudeva and mother of Balram), Subhadra (sister), Durga
(the girl child whom Kansa tried to kill as the eighth child of Deoki
& Vasudeva), Rukmini (wife), Satyabhma (wife) are worshipped by shastric rites and the idols are immersed in rivers the next day.

Generally men,women, even
children and old persons observe Nirjala Brat for the whole day and night,
or at least fast for the day and partake fruits and milk in the night.
They may also observe Ratri Jagran and spend the night in religious
discourse, singing Bhajans and Kirtan.

The day on which this
festival is celebrated has two interpretations :

The Grihasta celebrate it as
Krishnashtami. Hence, the day is decided by the fact that Ashtami must be
the Tithi at Sunrise time (Udaya Tithi). It may be succeeded by Navami but
never preseded by Saptami on the day. This is the common way of
celebration.

Sanyasis and Vaishnavs
celebrate Krishna Jayanti Brat and the day is decided by the fact that
Ashtami must encompass Rohini Nakshtra at Moon-rise time (near midnight).
Not very common